Georgia Tech Study Says Electric Trumps Diesel

With the cost of fuel an ever-present and painful problem for fleet managers, it’s no wonder there is increasing interest in everything that might help you conserve fuel. That includes electric engines. They’re not just for cars any more — the biggest names in trucks are introducing electric alternatives that can be worth a close look.

But how do electric trucks stack up against traditional diesel-powered vehicles? Researchers at Georgia Tech investigated, and based on their results under the delivery situations they tested, electric trucks came out on top.

The study compared life-cycle energy consumption, greenhouse gas emissions and total cost of ownership of medium-duty electric and diesel delivery trucks, in an urban environment. Specifically, the study used a Federal Express parcel delivery diesel truck of GVW class 5 (16,001-19,500 pounds) and a total of 219 SEV Newton electric trucks in 63 cities around the country.

The study included several different electricity generation scenarios and driving conditions, focusing on what’s known as the New York City Drive Cycle and the  Orange County (CA) Transportation Authority Cycle – in other words, low average speeds and frequent stops.

Total cost of ownership winds up being about the same for both types of vehicles.

Electric-powered engines perform more efficiently at lower speeds, but as average speeds rise, their advantage disappears. So diesel trucks were the better overall performers in City Suburban Heavy Vehicle (CSHVC) type driving conditions. In addition, the need to replace expensive batteries can significantly affect TCO, and there are issues surrounding environmentally friendly disposal of exhausted batteries.

Of course, ultimately efficiency depends on more than fuel consumption. So in addition to drive cycles, Georgia Tech’s team looked at factors such as truck utilization (the number of vehicle kilometers traveled). Typically, electric trucks have a more limited travel range based on battery charge than diesel trucks do based on a tank of fuel.

Researchers noted that lithium-ion batteries for electric vehicles are still evolving, and future improvements to their durability and reliability will correspondingly improve life-cycle energy consumption, greenhouse gas emissions and TCO.

Cost of electricity varies more than the cost of diesel.

In some states, power costs are very high, whereas elsewhere they are comparatively quite low. Obviously higher rates will drive up operations costs and total cost of ownership. Nonetheless, using projected future costs, the study indicated electric-powered trucks would show similar or slightly lower energy consumption and greenhouse gas emissions compared to diesel trucks in most of the country.

Here are some interesting statistics from the Georgia Tech study:

• Electric trucks use 28% less energy over their lifetime and emit 38% fewer greenhouse gasses than their diesel counter parts. This was true for the 2011-2012 year studied and also for projected 2025 costs.
• The diesel truck achieved a mere 4.6 mpg in theNew York City drive cycle scenario, whereas electric trucks demonstrated roughly half the lifetime energy use and emissions.
• Under the CHSVC driving scenario, the diesel averaged 8.6 mpg, whereas even the least efficient electric truck used 14% less energy and showed from 27% to 43% less greenhouse gas emissions.
• Exactly how the two types of trucks compare depends on how they’re used and where they’re located, but also on the efficiency of the electric vehicle’s powertrain. Results can also differ depending on the carbon intensity of regional electrical generation, giving electric trucks the widest advantage in the Pacific Northwest, the West and the Northeast.

Key factors that determine diesel truck TCO are fuel consumption, miles traveled and the price of fuel. Key factors that determine electric truck TCO are frequency and cost of battery replacement as well as other electric vehicle supply equipment costs. So while it’s not quite like comparing apples to apples, comparing total cost of ownership is well worth your time before you make your next delivery truck purchase.